The principal aim of this project is to elucidate the molecular mechanism of active transport in bacterial organisms. In this simple fermentative organism, Streptococcus faecalis, it is known that cellular accumulation of K ion and certain amino acids is coupled to ATP hydrolysis by an ATPase associated with the plasma membrane. In order to understand the coupling mechanism we are attempting to characterize the protein subunits in the ATPase and in the membrane sector with which the enzyme is associated. More particularly we are trying to isolate the protein components that are part of the "proton-channel" envisaged by the chemiosmotic theory. For this purpose we will use an isolated ATPase-membrane sector complex which is sensitive to the energy transfer inhibitor, dicyclohexylcarbodiimide. We are also trying to characterize a small peptide segment on the ATPase molecule which is involved in the attachment of the enzyme to the plasma membrane. This segment is selectively cleaved from the alpha chains by limited treatment of the isolated ATPase with chymotrypsin.